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Lubrication Theory
In fluid dynamics, lubrication theory describes the flow of fluids (liquids or gases) in a geometry in which one dimension is significantly smaller than the others. An example is the flow above air hockey tables, where the thickness of the air layer beneath the puck is much smaller than the dimensions of the puck itself. Internal flows are those where the fluid is fully bounded. Internal flow lubrication theory has many industrial applications because of its role in the design of fluid bearings. Here a key goal of lubrication theory is to determine the pressure distribution in the fluid volume, and hence the forces on the bearing components. The working fluid in this case is often termed a lubricant. Free film lubrication theory is concerned with the case in which one of the surfaces containing the fluid is a free surface. In that case, the position of the free surface is itself unknown, and one goal of lubrication theory is then to determine this. Examples include the flow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thin Fluid Film With Particles Flowing Down An Inclined Plane
Thin may refer to: * Thin (film), ''Thin'' (film), a 2006 documentary about eating disorders * Thin, a web server based on Mongrel (web server), Mongrel * Thin (name), including a list of people with the name * Mal language, also known as Thin See also * * * Body shape * Emaciation * Underweight * Paper Thin (other) * Thin capitalisation * Thin client, a computer in a client-server architecture network. * Thin film, a material layer of about 1 μm thickness. * Thin-layer chromatography (TLC), a chromatography technique used in chemistry to separate chemical compounds * Thin layers (oceanography), congregations of phytoplankton and zooplankton in the water column * Thin lens, lens with a thickness that is negligible compared to the focal length of the lens in optics * Thin Lizzy, Irish rock band formed in Dublin in 1969 * Thin Man (other) * The Thin Blue Line (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disjoining Force
In surface chemistry, disjoining pressure (symbol ) according to an IUPAC definition arises from an attractive interaction between two surfaces. For two flat and parallel surfaces, the value of the disjoining pressure (i.e., the force per unit area) can be calculated as the derivative of the Gibbs energy of interaction per unit area in respect to distance (in the direction normal to that of the interacting surfaces). There is also a related concept of disjoining force, which can be viewed as disjoining pressure times the surface area of the interacting surfaces. The concept of disjoining pressure was introduced by Derjaguin (1936) as the difference between the pressure in a region of a phase adjacent to a surface confining it, and the pressure in the bulk of this phase. Description Disjoining pressure can be expressed as:Hans-Jürgen Butt, Karlheinz Graf, Michael Kappl,"Physics and chemistry of interfaces", John Wiley & Sons Canada, Ltd., 1 edition, 2003, page 9(Google books)/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Blood Cells
Red blood cells (RBCs), referred to as erythrocytes (, with -''cyte'' translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, erythroid cells, and rarely haematids, are the most common type of blood cell and the vertebrate's principal means of delivering oxygen () to the body tissue (biology), tissues—via blood flow through the circulatory system. Erythrocytes take up oxygen in the lungs, or in fish the gills, and release it into tissues while squeezing through the body's capillary, capillaries. The cytoplasm of a red blood cell is rich in hemoglobin (Hb), an iron-containing biomolecule that can bind oxygen and is responsible for the red color of the cells and the blood. Each human red blood cell contains approximately 270 million hemoglobin molecules. The cell membrane is composed of proteins and lipids, and this structure provides properties essential for physiological Cell (biology), cell function such as erythrocyte deformabil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adhesive
Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advantages over other binding techniques such as sewing, mechanical fastenings, and welding. These include the ability to bind different materials together, the more efficient distribution of stress across a joint, the cost-effectiveness of an easily mechanized process, and greater flexibility in design. Disadvantages of adhesive use include decreased stability at high temperatures, relative weakness in bonding large objects with a small bonding surface area, and greater difficulty in separating objects during testing. Adhesives are typically organized by the method of adhesion followed by ''reactive'' or ''non-reactive'', a term which refers to whether the adhesive chemically reacts in order to harden. Alternatively, they can be organized either ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Painting
Painting is a Visual arts, visual art, which is characterized by the practice of applying paint, pigment, color or other medium to a solid surface (called "matrix" or "Support (art), support"). The medium is commonly applied to the base with a brush. Other implements, such as palette knives, sponges, airbrushes, the artist's fingers, or even a dripping technique that uses gravity may be used. One who produces paintings is called a painter. In art, the term "painting" describes both the act and the result of the action (the final work is called "a painting"). The support for paintings includes such surfaces as walls, paper, canvas, wood, glass, lacquer, pottery, leaf, copper and concrete, and the painting may incorporate other materials, in single or multiple form, including sand, clay, paper, cardboard, newspaper, plaster, gold leaf, and even entire objects. Painting is an important form of visual arts, visual art, bringing in elements such as drawing, Composition (visual art ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Printing
Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The earliest known form of printing as applied to paper was woodblock printing, which appeared in China before 220 AD for cloth printing. However, it would not be applied to paper until the seventh century.Shelagh Vainker in Anne Farrer (ed), "Caves of the Thousand Buddhas", 1990, British Museum publications, Later developments in printing technology include the movable type invented by Bi Sheng around 1040 AD and the printing press invented by Johannes Gutenberg in the 15th century. The technology of printing played a key role in the development of the Renaissance and the Scientific Revolution and laid the material basis for the modern knowledge-based economy and the spread of learning to the masses. History Woodblock printing Woodblo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thin Films
A thin film is a layer of materials ranging from fractions of a nanometer ( monolayer) to several micrometers in thickness. The controlled synthesis of materials as thin films (a process referred to as deposition) is a fundamental step in many applications. A familiar example is the household mirror, which typically has a thin metal coating on the back of a sheet of glass to form a reflective interface. The process of silvering was once commonly used to produce mirrors, while more recently the metal layer is deposited using techniques such as sputtering. Advances in thin film deposition techniques during the 20th century have enabled a wide range of technological breakthroughs in areas such as magnetic recording media, electronic semiconductor devices, integrated passive devices, light-emitting diodes, optical coatings (such as antireflective coatings), hard coatings on cutting tools, and for both energy generation (e.g. thin-film solar cells) and storage ( thin-film ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coating
A coating is a covering that is applied to the surface of an object, or substrate. The purpose of applying the coating may be decorative, functional, or both. Coatings may be applied as liquids, gases or solids e.g. powder coatings. Paints and lacquers are coatings that mostly have dual uses, which are protecting the substrate and being decorative, although some artists paints are only for decoration, and the paint on large industrial pipes is for identification (e.g. blue for process water, red for fire-fighting control) in addition to preventing corrosion. Along with corrosion resistance, functional coatings may also be applied to change the surface properties of the substrate, such as adhesion, wettability, or wear resistance.Howarth G.A "Synthesis of a legislation compliant corrosion protection coating system based on urethane, oxazolidine and waterborne epoxy technology" Master of Science Thesis April 1997 Imperial College London In other cases the coating adds a co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seal (mechanical)
A seal is a device or material that helps join systems, mechanisms or other materials together by preventing leak, leakage (e.g. in a wikt:pumping, pumping system), containing pressure, or excluding contamination. The effectiveness of a seal is dependent on adhesion in the case of sealants and compression in the case of gaskets. The seals are installed in pumps in a wide range of industries including chemicals, water supply, paper production, food processing and many other applications. A stationary seal may also be referred to as a 'packing'. Seal types: *Induction sealing or cap sealing *Sealant, Adhesive, sealant *Bodok seal, a specialized gas sealing washer for medical applications *Bonded seal, also known as Dowty Group, Dowty seal or Dowty washer. A type of Washer (hardware), washer with integral gasket, widely used to provide a seal at the entry point of a screw or bolt *Bridgman seal, a piston sealing mechanism that creates a high pressure reservoir from a lower pressure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lubrication
Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology. Lubrication mechanisms such as fluid-lubricated systems are designed so that the applied load is partially or completely carried by hydrodynamic or hydrostatic pressure, which reduces solid body interactions (and consequently friction and wear). Depending on the degree of surface separation, different lubrication regimes can be distinguished. Adequate lubrication allows smooth, continuous operation of machine elements, reduces the rate of wear, and prevents excessive stresses or seizures at bearings. By repelling water and other substances, it also reduces corrosion. When lubrication breaks down, components can rub destructively against each other, causing heat, local welding, destructive damage and failure. Lubrication mechanisms Fluid-lubricated systems As the load incre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reynolds Equation
In fluid mechanics (specifically lubrication theory), the Reynolds equation is a partial differential equation governing the pressure distribution of thin viscous fluid films. It was first derived by Osborne Reynolds in 1886. The classical Reynolds Equation can be used to describe the pressure distribution in nearly any type of fluid film bearing; a bearing type in which the bounding bodies are fully separated by a thin layer of liquid or gas. General usage The general Reynolds equation is: \frac\left(\frac\frac\right)+\frac\left(\frac \frac\right) = \frac \left(\frac\right)+\frac \left(\frac\right)+\rho\left(w_a-w_b\right) - \rho u_a\frac - \rho v_a \frac + h\frac Where: *p is fluid film pressure. *x and y are the bearing width and length coordinates. *z is fluid film thickness coordinate. *h is fluid film thickness. *\mu is fluid viscosity. *\rho is fluid density. *u, v, w are the bounding body velocities in x, y, z respectively. *a, b are subscripts denoting the top and bot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscosity
Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup has a higher viscosity than water. Viscosity is defined scientifically as a force multiplied by a time divided by an area. Thus its SI units are newton-seconds per metre squared, or pascal-seconds. Viscosity quantifies the internal friction, frictional force between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tube's center line than near its walls. Experiments show that some stress (physics), stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
